Auto Manufacturing Ltd. provides the following comparative financial data for the years ended December 31, 2021, 2020, and 2019.

Description	2021	2020	2019
Revenue	$10,000,000	$9,500,000	$9,000,000
Cost of Goods Sold	$6,000,000	$5,700,000	$5,400,000
Gross Profit	$4,000,000	$3,800,000	$3,600,000
Operating Expenses	$2,000,000	$1,900,000	$1,800,000
Operating Income	$2,000,000	$1,900,000	$1,800,000
Interest Expense	$400,000	$380,000	$360,000
Earnings Before Tax	$1,600,000	$1,520,000	$1,440,000
Tax Expense	$320,000	$304,000	$288,000
Net Income	$1,280,000	$1,216,000	$1,152,000

Requirements:

1. Prepare a common-size income statement for each year.
2. Calculate the Operating Expense Ratio for each year.
3. Determine the Interest Coverage Ratio for each year.
4. Evaluate the company's financial health over the three years.